Post-Term Pregnancy

What is a post-term pregnancy?

A pregnancy that lasts more than 42 weeks is called post-term. A pregnancy that is between 41 and 42 weeks is called late-term. Most women deliver between 37 and 42 weeks of pregnancy.

What causes post-term pregnancy?

Healthcare providers do not know why some women carry a pregnancy longer than others. It is often because of miscalculating the due date. You are also more likely to have a post-term pregnancy if you:

Are pregnant with your first baby

Had past pregnancies that went past 42 weeks

Are overweight

Are having a boy

What are the symptoms of post-term pregnancy?

There are no symptoms of a post-term pregnancy.

How is post-term pregnancy diagnosed?

To calculate you due date, your healthcare provider will:

Measure the size of your uterus at certain points in early pregnancy

Note the date he or she first hears your developing baby's heartbeat

Note when you first feel your baby moving in your uterus

Use ultrasound

In a post-term pregnancy, your healthcare provider may do testing to check on your baby's well-being and for problems. Tests may include:

Ultrasound

Seeing how your baby's heart rate responds to activity

Checking the amount of amniotic fluid

How is post-term pregnancy treated?

The goal is to prevent problems and deliver a healthy baby. Your healthcare provider will base specific treatment on your pregnancy, age, and general health. It will also depend on how severe the condition is.

Your healthcare provider may do maternal and fetal testing to watch for problems. Tests include:

Fetal movement counting.This keeps track of your baby's kicks and movements. A change in the number or frequency may mean the developing baby is under stress.

Biophysical profile.This test combines the non-stress test with an ultrasound to look at your baby's well-being.

Ultrasound. This test uses high-frequency sound waves and a computer to make images of blood vessels, tissues, and organs. Ultrasounds are also used to follow the growth of your developing baby.

Doppler flow studies. This is a type of ultrasound that uses sound waves to measure blood flow. The test is commonly used if a developing baby is not growing normally.

If tests find that it is not healthy for the developing baby to stay in your uterus, your healthcare provider may induce labor to deliver the baby. Your healthcare provider will talk with you about the decision to induce labor.

Once labor begins, your provider will monitor your baby's heart rate with an electronic monitor. This is done to watch for changes in the heart rate caused by low oxygen levels. You may need a cesarean delivery if your baby's condition changes.

Amnioinfusion is sometimes used during labor if there is very little amniotic fluid or if the baby is pressing on the umbilical cord. A sterile fluid is put into the uterus with a hollow tube (catheter). The fluid helps replace the amniotic fluid and cushions the baby and cord.

What are possible complications of a post-term pregnancy?

Women with post-term pregnancy, especially with a large baby, are more likely to have:

Longer labor

Forceps or vacuum-assisted birth

Vaginal tearing or injury

Cesarean delivery

Infection, wound complications, and bleeding after birth

There are also risks for the unborn and newborn baby in a post-term pregnancy. These include:

Stillbirth and newborn death

Placenta problems

Decreased amniotic fluid

The baby may stop gaining weight, or may even lose weight

Birth injury if the baby is large

Baby breathes in fluid containing the first stool (meconium aspiration)

When should I call my healthcare provider?

Once your pregnancy has reached 37 weeks, you will have weekly appointments with your healthcare provider. If your pregnancy goes past 41 weeks, you and your healthcare provider will talk about your options. You will also decide how often you need to be seen to check your pregnancy and the health of your baby. It is important to keep all of your appointments.